Japan's Mutsu Spent Fuel Interim Storage Facility May Expand Participants; KEPCO and Hokuriku Electric Power Say They Are Considering

Tokyo Electric Power Company (TEPCO) and Japan Atomic Power Company (JAPC) began contacting eight other domestic electric power companies that own nuclear power plants on August 10, asking whether they would be interested in participating in the expansion of the entities responsible for transporting spent fuel to the interim storage facility in Mutsu City, Aomori Prefecture.

Among the eight companies contacted, Kansai Electric Power Company (KEPCO) and Hokuriku Electric Power Company indicated in response to the inquiries that they are considering whether to participate. In December 2025, TEPCO and JAPC had submitted a proposal to Aomori Prefecture and Mutsu City regarding the expansion of operating entities, and at that time they had also sought the intentions of these eight companies, but no electric power company had clearly indicated that it was considering participation.

The so-called "inter-operator cooperation" means that, in addition to TEPCO and JAPC, other electric power companies would also be able to transport spent fuel into the interim storage facility. This arrangement is in effect close to joint use of the facility. However, the siting agreement concluded with the local community was not premised on the expansion of operating entities. The city of Mutsu agreed on the 7th to conduct a detailed review of the relevant proposal.

TEPCO stated that as of the 10th, it had not received any formal responses from electric power companies regarding participation. KEPCO said in response to the inquiry that it is "considering whether to actually participate, including whether to participate at all." In December 2025, the company had stated that the matter involved other companies and therefore declined to comment. The average storage rate of spent fuel pools at KEPCO's three nuclear power plants in Fukui Prefecture is approximately 90%.

Hokuriku Electric Power stated that it is "considering matters including participation." The spent fuel storage rate at the Shika Nuclear Power Station in Ishikawa Prefecture is approximately 20%. The company had previously stated that its existing storage capacity is sufficient to sustain operations for 10 to 16 years.

The other electric power companies have not yet made clear statements. Chugoku Electric Power Company stated that it would "consider a response in the future"; Hokkaido Electric Power Company also said it would "consider a response in the future," without specifying details. Tohoku Electric Power Company, Chubu Electric Power Company, and Shikoku Electric Power Company stated that they had "no comment" or "could not respond"; Kyushu Electric Power Company stated that it "could not respond on the 10th."

TEPCO and JAPC have proposed a plan to maintain the operation of the Mutsu City interim storage facility through the 2090s. On the other hand, the total amount of spent fuel currently expected to be transported into the facility is lower than the initially envisioned 5,000 tons. Due to concerns over reduced tax revenue and subsidies, some local residents have called for studying the possibility of expanding the number of operating entities.